JP2910939B2 - Operation control method of vertical melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for controlling the operation of a vertical melting furnace in which a raw material such as a metal lump is charged to obtain a constant amount of melt.

[0002]

2. Description of the Related Art A vertical melting furnace has a furnace body having an inlet into which a raw material such as a metal lump is charged and an outlet through which a melt is discharged, and a plurality of combustion furnaces arranged in multiple stages in the furnace body. Combustion means comprising a burner, and the raw material flows out of the outlet while being melted by the plurality of combustion burners. The melt flowing out from the outlet of the furnace body is accumulated in the melt holding furnace through the inclined melt passage, and is guided from the holding furnace to an appropriate processing means.

On the other hand, in the vertical melting furnace, unmelted raw materials fall from the furnace wall and block the outlet of the furnace, so that the melt is stagnant so that the amount of the melt flowing out of the outlet decreases. Outlet clogging abnormality may occur. Further, the undissolved material may be caught in a bridge shape on the furnace wall in the furnace, and a shelf hanging abnormality may occur in which the outflow amount of the melt decreases.

[0004] In the prior art, the operator directly visually monitors the outflow of the melt from the outlet of the melting furnace or the amount of the melt accumulated in the holding furnace, and the outflow or the amount of the melt decreases. In such a case, the strength of a plurality of combustion burners is adjusted at the same time based on the empirical judgment of the operator to maintain the outflow of the melt in a certain range.

[0005]

However, in this prior art, the operation of the combustion burner is adjusted depending on the empirical judgment of the operator, so that the operation control becomes unstable depending on the skill of the operator and the melting of the combustion burner becomes unstable. Since the outflow of the material increased or decreased, the melting furnace could not be operated stably, so that a large amount of energy was consumed and it was inefficient. Further, in this conventional technique, there is a drawback that the workability is low because the operator must constantly monitor the outflow amount or the retained amount of the dissolved matter visually.

An object of the present invention is to provide a method for controlling the operation of a vertical melting furnace capable of obtaining a constant flow rate of molten material without requiring empirical judgment of an operator and with a minimum energy consumption. Is to provide.

Another object of the present invention is to provide a method for controlling the operation of a vertical melting furnace in which an operator can always obtain a constant amount of melt without monitoring the amount of the melt flowing out or accumulated. Is to do.

[0008]

One of the objects of the present invention is to operate a vertical melting furnace having a plurality of combustion burners arranged in a plurality of stages and to operate the vertical melting furnace. It is an object of the present invention to provide an operation control method of a vertical melting furnace in which the combustion intensity is adjusted so as to gradually increase or decrease from the upper stage to the lower stage.

According to another aspect of the present invention, there is provided the above-described one aspect of the present invention, wherein the combustion intensity of the plurality of combustion burners and the inclination thereof are fed back from the outflow or accumulation amount of the melt in the vertical melting furnace. An object of the present invention is to provide an operation control method of a vertical melting furnace determined based on a signal.

[0010]

As described above, melting is performed by using the combustion pattern in which the combustion intensity of the plurality of combustion burners of the vertical melting furnace increases gradually from the upper stage to the lower stage and the combustion pattern gradually decreases from the upper stage to the lower stage. Adjusting these combustion patterns or intensities when the outflow or accumulation of material is reduced or increased can effectively transfer heat from the combustion burner to the raw material and waste heat energy. Absent. Also,
When the amount of effluent or accumulation of the melt decreases, switch to one of the combustion patterns and control the operation of the smelting furnace while checking how the effluent of the melt changes accordingly. It is possible to keep the amount of outflow of goods constant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described in detail. FIG. 1 shows a vertical melting furnace control apparatus 10 used to carry out the method of the present invention. The vertical melting furnace 12 has a furnace body 20 having an inlet 16 into which a raw material 14 such as a metal lump is introduced, and an outlet 18 through which a melt flows out, and a plurality of stages arranged in the furnace body 20 in multiple stages. It comprises a combustion burner, in the embodiment shown combustion means 24 comprising three combustion burners 22A, 22B, 22C.

A predetermined pressure of fuel (combustion gas) is supplied to the combustion burner 22A from a fuel supply source 42 via a motor drive valve 26, and the motor drive valve 26 is driven by a motor 28. Similarly, fuel of a predetermined pressure is supplied to the combustion burners 22B and 22C via a similar motor-driven valve (not shown). The combustion pressure of each combustion burner is detected by a pressure sensor 32 from a manifold 30 that distributes fuel to each burner.

A control means 34 for supplying control signals Sa, Sb, Sc to the motor of the motor drive valve 26 for controlling the combustion state of the melting furnace 12 is provided.
Consists of a CPU such as a computer. This C
As will be described later, the PU adjusts the control signals Sa, Sb, Sc so as to determine the combustion state of the combustion means 24 from, for example, a change in the storage amount of the melt.

The raw material 14 flows out of the outlet 18 while being melted by the plurality of combustion burners 22A, 22B, 22C in the furnace body 20. Thus, the furnace body 2
The melt that has flowed out of the outlet 18 is discharged to the melt passage 36.
Then, the melt is accumulated in the holding furnace 38 for the melt, and guided from the holding furnace 38 to appropriate processing means. The holding furnace 38 is tiltably supported by furnace tilting means (not shown), and by adjusting the tilt angle, the amount of the melt that can be held inside can be changed. The amount of the melt flowing out of the holding furnace 38 is controlled by adjusting the tilt angle.

The control device 10 includes a melt detection means 40 for detecting the amount of the melt flowing out from the outlet 18 or the amount of the melt accumulated in the holding furnace 38. In the illustrated embodiment, the melt detection means 40 detects the amount of the melt accumulated in the holding furnace 38. This dissolved substance detection means 40
For example, the flow rate of the melt may be detected by directly measuring the accumulated weight of the holding furnace 38 or indirectly measuring the tilt angle of the holding furnace 38 by an encoder and a counter. The amount may be detected. The lysate signal Sf corresponding to the effluent amount of the lysate detected in this way is input to the control means 34.

As can be seen from FIG. 1, the CPU is provided between the fuel supply source 42 and the front of the branch pipes 21A to 21C branched to the respective combustion burners 22A to 22C. The control system includes a flow meter 44 for detecting a flow rate of fuel (combustion gas) supplied to the fuel cell 22C, and a fuel consumption measuring circuit 46 for generating a fuel signal Sfu corresponding to the fuel consumption according to the flow meter 44. Means 3
4 is the fuel signal Sfu from the fuel consumption measuring circuit 46.
To calculate the amount of stored melt per unit consumption of fuel.

According to the method of the present invention, the combustion intensity of the plurality of combustion burners of the combustion means 24 is changed or the combustion pattern of these combustion burners is switched according to the change of the melt signal Sf. As shown in FIG. 2, the combustion pattern includes a first combustion pattern in which the combustion intensities of the plurality of combustion burners 22A to 22C are gradually increased from the upper stage to the lower stage, and as shown in FIG. Plural combustion burners 22A to 22A
A second combustion pattern in which the combustion intensity of C gradually decreases from the upper stage to the lower stage, and the CPU switches to any one of the combustion patterns according to a change in the storage amount of the melt, or Change the burning intensity with the same burning pattern. 2 and 3, the combustion burners 22A to 22A
The length of the arrow 2C is shown in proportion to the combustion intensity.

Next, the method of the present invention will be described in detail with reference to FIGS. 2 and 3. The raw material 14 is charged into the melting furnace 12 through the charging port 16, and the combustion means 24 is driven to drive the melting furnace 1.
Start 2 All operations from the start of the melting furnace to the normal state are controlled by the control means 34. When the melting furnace 12 is started, the control means 34 adjusts the opening degree of the motor drive valve 26 so as to drive all the combustion burners 22A to 22C with the same combustion intensity and with a large combustion intensity.

The molten material flows out of the melting furnace 12 and the holding furnace 3
When the amount of melt in the melt 8 reaches a predetermined amount and further increases in the amount of melt thereafter, the control means 34 receives a corresponding melt signal Sf and estimates the combustion burners 22A to 22C to the first or the second. The control signals Sa to Sc are output so as to temporarily adjust to any of the second combustion patterns. If the amount of accumulated molten matter still tends to increase, control is performed so as to reduce the combustion intensity of the combustion burners A to 22C with the same combustion pattern. After a certain period of time, if the amount of the melt still tends to increase, the control means 34 controls the combustion intensity of the combustion burners 22A to 22C to be further reduced without changing the combustion pattern.

Conversely, the amount of accumulated lysate tends to decrease, and the control means 34 causes the corresponding lysate signal Sf
In response, the control means 34 outputs control signals Sa to Sc so as to switch the combustion pattern. This is based on the assumption that the decrease in the melt signal Sf is based on either the clogging of the outlet of the melting furnace 12 or the abnormality of hanging the shelf, and the first combustion pattern
(Fig. 2), and in the latter case, the second combustion pattern
(FIG. 3) . At the same time as this switching, the combustion intensity is increased with a new combustion pattern. After a certain period of time, if there is a tendency for the accumulated amount of the melt to further decrease, the control means 34 outputs control signals Sa to Sc so as to switch another combustion pattern to increase the combustion intensity.

If it is detected that the accumulated amount of the dissolved matter tends to increase as a result of switching to the new combustion pattern, the control means 34 causes the new combustion pattern to cause a decrease in the outflow amount of the dissolved matter. If it is determined that it is most suitable for eliminating a certain outlet clogging or hanging on a shelf, and therefore the amount of the accumulated melt exceeds a predetermined value, a control signal is given so as to reduce the burning intensity in the same burning pattern. Sa to Sc are output.

In this way, if the accumulated amount of dissolved matter decreases, the current combustion pattern is determined to be inappropriate and the combustion pattern is switched. If the accumulated amount of dissolved matter increases, the current combustion pattern becomes If it is determined that the pattern is optimal and this combustion pattern is maintained and the amount of accumulation continues to increase, a predetermined amount of melt can be obtained by reducing the combustion intensity with the same combustion pattern.

In this case, when the plurality of combustion burners 22A to 22C are inclined from the upper stage to the lower stage so as to increase or decrease the combustion intensity in any of the combustion patterns, all the combustion burners 22A to 22C have the same combustion intensity. It is possible to operate with extremely high combustion efficiency as compared with the case where the pressure is maintained. That is, the first combustion pattern in FIG. 2 has a large combustion intensity in the lower stage, and is a combustion pattern effective for so-called outlet clogging, and the second combustion pattern in FIG. 3 has a large combustion intensity in the upper stage. This is a combustion pattern effective for so-called shelf hanging abnormalities. And the decrease in the amount of effluent (accumulation) of the melt
This is due to one of these abnormalities, so the combustion pattern is switched according to the decrease in the amount of accumulated melt, and if the melt turns to an increasing tendency after switching, then only the combustion intensity is adjusted with the same combustion pattern As a result, a certain amount of lysate can be obtained.

The control means 34 receives a melt signal Sf corresponding to the accumulated amount of the melt and a fuel signal Sfu corresponding to the fuel consumption at predetermined time intervals, for example, every 10 minutes. The difference from the target value and the temporal change rate of the accumulated amount of the dissolved matter are calculated, and the control signals Sa to Sc indicating the combustion pattern and its strength are determined. Also, the lysate signal Sf
The control means 34 switches to the first or second combustion pattern in accordance with the above, and the degree of combustion intensity can be determined by fuzzy calculation. In this fuzzy calculation, for example, the difference between the actual value and the target value of the amount of accumulated molten material in the holding furnace, the rate of change of the amount of accumulated molten material, and the opening degrees of the combustion burners 22A to 22C in one of the two combustion patterns A rule can be constructed based on the three evaluation functions. Further, in the above embodiment, the outflow amount of the melt is obtained from the accumulated amount in the holding furnace 38. However, the outflow amount of the melt may be directly detected.

FIGS. 4 and 5 show the total fuel consumption (fuel consumption) when a certain amount of melt is obtained by adjusting the combustion pattern and its intensity according to the melt signal Sf according to the method of the present invention. The change state of the signal Sfu) and the change state of the total fuel consumption (fuel signal Sfu) consumed when a certain amount of melt is obtained by a conventional method are shown. still,
In the conventional method, the intensities of the combustion burners A to 22C are all set to the same intensity, and the intensity is adjusted according to the melt signal Sf. As can be seen from these figures, according to the method of the present invention, the total fuel consumption is extremely smaller than that of the conventional method, and as a result of actual calculation, the total fuel consumption of the present invention is 3 times smaller than that of the conventional method. % Was confirmed.

[0026]

According to the present invention, as described above, the combustion pattern of the plurality of combustion burners of the vertical melting furnace is increased from the upper stage to the lower stage, and the combustion pattern is gradually decreased from the upper stage to the lower stage. With the use of different combustion patterns, when the outflow or accumulation of the melt decreases or increases, these combustion patterns and intensity are adjusted so that heat is effectively transferred from the combustion burner to the raw material. Therefore, it is possible to operate the melting furnace efficiently with a small amount of fuel consumption, and to switch to one of the combustion patterns in accordance with a change in the amount of the melt discharged or accumulated, and to determine the amount of the melt discharged accordingly. The operation of the melting furnace is controlled while checking whether the change will occur.Therefore, there is no need for the operator to work empirically while visually observing the amount of the melt discharged or accumulated in the melting furnace, and the melting furnace should be operated stably. In There is that practical benefits.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of an apparatus for performing the method of the present invention.

FIG. 2 is a schematic view of a first combustion pattern of the present invention.

FIG. 3 is a schematic view of a second combustion pattern of the present invention.

FIG. 4 is a diagram showing a change in fuel consumption used in a vertical melting furnace controlled by the method of the present invention.

FIG. 5 is a diagram showing a change in fuel consumption used in a vertical melting furnace controlled by a method according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vertical melting furnace control apparatus 12 Vertical melting furnace 14 Raw material 16 Input port 18 Outlet 20 Furnace main body 22A to 22C Combustion burner 24 Burning means 34 Control means 38 Holding furnace 40 Melt detection means 42 Fuel supply source 44 Flow meter Sa To Sc control signal Sf melt signal Sfu fuel signal

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-291490 (JP, A) JP-A-4-17632 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) F27B 1/00-1/28 F27D 13/00

Claims (2)

(57) [Claims] 1. A method for controlling the operation of a vertical melting furnace having combustion means comprising a plurality of combustion burners arranged in multiple stages, wherein the combustion intensity of the plurality of combustion burners of the combustion means is changed from an upper stage to a lower stage. A method for controlling the operation of a vertical melting furnace, characterized in that it is adjusted by inclining so as to become stronger or weaker one after another. 2. The method according to claim 1, wherein the combustion intensity and the inclination of the plurality of combustion burners are determined based on a feedback signal from the outflow or accumulation of the melt.
4. The operation control method for a vertical melting furnace according to 1.